On stardate 2712.4, the Enterprise reached Exo III. Korby was found, exploring and exploiting a sophisticated android manufacturing technology, the legacy of a long-dead civilization. Korby had replaced his own damaged body, transplanting his personality into an android replica, and had built himself a beautiful companion, Andrea. After exhibiting his madness, the android Korby was destroyed. Initially, Chapel doubted if she should stay aboard, but she elected to remain with the Enterprise throughout the five-year mission. (TOS: "What Are Little Girls Made Of?")

By 2267, there were occasional times when Chapel was called upon to help other doctors, sometimes with McCoy as the patient. She also knew when it was a good idea to be supportive of Dr. McCoy, even when others questioned whether he could be entirely reliable. On stardate 3478.2, such an event happened. When Kirk, Spock, McCoy, Scott, and LieutenantArlene Galway contracted a mysterious rapid-aging syndrome on the planet Gamma Hydra IV due to radiation left by a passing comet, Chapel was called upon to help the visiting Dr. Janet Wallace in an effort to help comfort, if not cure, Kirk, Spock, McCoy, Scott, and Galway. (Unfortunately, before a cure was discovered, Galway died of old age.) Later, when Dr. McCoy, with Spock's help, figured out that it was increased adrenaline levels that had kept Ensign Pavel Chekov from developing the syndrome, Chapel instinctively knew that McCoy would be able to figure out an antidote for the rapid-aging syndrome in time to cure himself, Kirk, Spock, and Scott. She stood up for McCoy even while that wisdom was questioned by Dr. Wallace and visiting CommodoreStocker, but let it be known that Dr. Wallace could be of great assistance to her and McCoy. Sure enough, Chapel's wisdom was borne out when McCoy did find the antidote in time to save himself, Kirk, Spock, and Scott. (TOS: "The Deadly Years")

In 2268, though, there were times both when Dr. McCoy greatly confused Chapel, as well as when she was put into danger. On stardate 4657.5, Chapel was in the Enterprisesickbay when McCoy and the KelvanTomar brought in Spock from the surface of a class M planet where a landing party had met the Kelvans. McCoy told Chapel that Spock was close to dying, though she could tell that wasn't true. This was a ruse by both McCoy and Spock on Kirk's orders, because Kirk wanted them on the ship to help stop the Kelvans from taking the ship to the Andromeda Galaxy, and Spock had put himself into a Vulcan trance to trick the Kelvans into thinking he was truly gravely ill. McCoy had to hint to Chapel to keep quiet. She did take the hint but remained confused. On stardate 4658.9, the Kelvans still hijacked the Enterprise to return to the Andromeda Galaxy and Dr. McCoy complained to Kirk that he had watched four of his best doctors and nurses, including Chapel, be neutralized and reduced into dehydrated porous cuboctahedron solids, the size of a Human fist, composed of their base minerals, which represented the "distilled" essences of their beings. The Kelvans considered them non-essential personnel. Chapel and the other doctors and nurses were reconstituted, after Kirk, Spock, McCoy and Scott, the only four not neutralized, regained control of the Enterprise. (TOS: "By Any Other Name")

On stardate 5029.5, when children from the Starnes Exploration Party were on board the Enterprise, she cared for and entertained them, showing them how they could use food cards to order any ice cream they wished from the Enterprise's replicators. She also was the first to notice how the children didn't cry for their recently deceased parents, and reported this observation to Dr. McCoy. (TOS: "And the Children Shall Lead")

Chapel and McCoy administer the tri-ox compound to Kirk, in the transporter room after Kirk was rescued from the Defiant.

On two separate occasions, Chapel displayed excellent skills as a lab assistant. On stardate 5693.2, she assisted Dr. McCoy in developing a diluted theragen derivative to cure mental degradation effects caused by an interphase as the Enterprise was passing through Tholian space. She also assisted McCoy by administering the cure throughout the ship and helping him, in the transporter room, in administering the tri-ox compound to Kirk after he was beamed aboard from the USS Defiant. On stardate 5710.5, Chapel assisted Spock and McCoy in synthesizing an agent to counteract hyper-acceleration effects of Scalosian water. (TOS: "The Tholian Web", "Wink of an Eye")

On stardate 5143.3, she informed McCoy that Captain Kirk wanted to know whether his examination of "Carter Winston" was finished, adding that his fiance Anne Nored was waiting to see him. (TAS: "The Survivor")

On stardate 5483.7 when under the influence of the women of planet two of the Taurean system, the male crew members of the Enterprise were incapacitated by the siren's song. Lieutenant Uhura took command of the vessel, and assigned Chapel as acting chief medical officer. They led an all-female landing party down to the planet's surface to rescue Captain Kirk, Spock, and Dr. McCoy. (TAS: "The Lorelei Signal")

On stardate 5499.9 when Kirk and Spock mutated into water-breathers, Chapel assisted Dr. McCoy in reversing their mutations. (TAS: "The Ambergris Element")

At some point prior to stardate 5577.5, Chapel acquired a titanium bracelet made by the titanium smiths of Libra, which she occasionally wore while on duty.

On stardate 5577.5, after the Enterprise was struck by a flash of light coming from a planet in the Cepheus star system and the flash temporarily paralyzed the crew, the whole crew started shrinking to fingernail length, at 1/16th of an inch in height. On stardate 5577.6, Spock observed that Chapel's titanium bracelet was staying the same mass, though their uniforms were shrinking at a proportional rate as their bodies. Spock hypothesized (correctly) that their Starfleet uniforms were shrinking because they were made of an algae-based material known as xenylon, and that biological and naturally made material objects were also shrinking, but not the ship itself or other totally man-made material objects.

A shrunken Chapel drowning

A short time later, after Lieutenant Sulu broke his right leg in a fall from the helm station on the bridge and was taken to sickbay by Kirk and Lieutenant Arex, Chapel fretted that they couldn't use their bone-knitting laser, as it was now too large. Chapel then had an idea that McCoy thought was a great idea: they could use a microscope laser, which they used to heal the inner ear, to do the surgery to reset and heal Sulu's leg. Chapel was proved correct about that, but – due to her shrinking size, while trying to bring the microscope laser from the medical cabinet – she tripped on a knitting needle that had also stayed the same size, fell into the sickbay's aquarium, and nearly drowned. Fortunately, Kirk was able to save her.

Later, Chapel helped rescue mutant descendants of the Terra 10colony from an unstable planet they were located on and relocate them to a more stable planet. Along with the rest of the crew, she was returned to her normal height by use of the transporter, which had saved the original molecular structure of each crew member in the pattern buffers. (TAS: "The Terratin Incident")

Chapel earned her MD after completing a medical program. In the mid-2270s, Chapel was assigned to the refittedEnterprise. Upon the return of Dr. McCoy during the V'ger crisis, he explained to Kirk that he was "going to need a top nurse, not a doctor who will argue every little diagnosis with me." Chapel later performed medical scans on the Ilia probe, and assisted in reacquainting the probe with Ilia's former life. She also provided medical care to Spock after his traumatizing mind meld with V'ger. (Star Trek: The Motion Picture)

According to the TMPnovelization, Chapel was supposed to be the Enterprise's chief medical officer, but the arrival of McCoy changed that. Chapel was very pleased that he was CMO and she wasn't.

In 2286, Commander Chapel was stationed at Starfleet Headquarters, where she coordinated relief efforts while Earth was suffering a severe ecological "attack" from an orbiting space probe. Later, Chapel attended the trial of Kirk and his senior officers at the Federation Council Chambers and excitedly congratulated her old crewmates when the council dismissed all charges facing them. (Star Trek IV: The Voyage Home)

While serving as a nurse, Chapel considered her responsibilities as a member of the medical profession to supersede her role as a subordinate crew member on the Enterprise, even to the point of disobeying an order from her superior, McCoy, whose welfare she was concerned about. (TOS: "For the World is Hollow and I Have Touched the Sky")

Once she used nursing as an excuse for a romantic gesture towards Spock, bringing him plomeek soup, as he had not been eating for three days due to his recent nervous state. Though her actions initially met with the Vulcan's ire, he eventually warmed up to her and apologized, asking for more soup. (TOS: "Amok Time")

Chapel became engaged to Korby after having been a student of his. Despite his disappearance and the failure of two previous expeditions to find him, she maintained her hope of doing so. When asked by Spock if she recognized his voice, she remembered it clearly enough to confirm that it was, in fact, Roger who was contacting the Enterprise.

Upon arriving on Exo III, she embraced him tenderly, only to become jealous of Andrea's familiarity with him, as the android also called Korby by his first name. Upon being told that Andrea was an android, she naturally assumed he'd created a companion to replace her, or, as she put it, a "mechanical geisha". Korby assured her that Andrea only obeyed orders and that he did not consider her a woman, merely a tool.

Having learned of Korby's ability to manufacture android duplicates of living people, and seeing what became of the other members of the landing party, she was disillusioned, recalling that the Korby she knew wouldn't harm a living creature, believing their life sacred. She was still conflicted about his mental state, and hoped not to be given orders to betray him, preferring instead to have "Kirk" "push me off the same precipice where Mathews died. ".

Though he tried to convince her he was still the same man he had always been inside, she refused to believe him. Upon the destruction of his android body and subsequent death, she returned to the Enterprise. (TOS: "What Are Little Girls Made Of?")

Even while she still sought to locate Korby, Chapel was deeply infatuated with the Enterprise's half-Vulcanscience officer, Spock. Her attraction to him was an ongoing source of tension and bemusement throughout the five-year mission.

Initially Chapel kept these feelings to herself. However, when the Psi 2000 intoxication afflicted the crew of the Enterprise, Chapel admitted her love for Spock, who was shocked:

"I'm in love with you, Mr. Spock. You, the Human Mr. Spock... the Vulcan Mr. Spock.... I see things... how honest you are. I know how you feel. You hide it, but you do have feelings. Oh, how we must hurt you... torture you."

Chapel insisted that Spock address her by her first name, as opposed to her title, which he resisted. Chapel was unaware that Spock's inability to react to her emotionally was further complicated by his betrothal to T'Pring. Leading him to the ceremony in which his fiancée rejected him in favor of a different suitor, Spock underwent a period of intense emotional outbursts: a blood fever known as pon farr. Chapel characteristically doted after the Vulcan, preparing plomeek soup, a traditional Vulcan broth. The experience allowed them to discuss, even if briefly, Chapel's confession of love. Despite his acknowledged inability to return her affections, he did refer to her as Christine for the first time. (TOS: "The Naked Time", "Amok Time")

Chapel's longing for Spock was well-known among crew members, and noted openly by Captain Kirk and Dr. McCoy on a number of occasions. During Spock's recovery after a near-death experience on Neural, fellow medical officer Dr. M'Benga caught Chapel tenderly holding Spock's hand while watching his recovery on the medical panel atop his bed. M'Benga was sympathetic, despite Chapel's attempt to hide her feelings. Chapel later proactively aided Spock by secretly holding his consciousness to keep him from being destroyed by Henoch. (TOS: "A Private Little War", "Return to Tomorrow")

Her feelings for the Vulcan briefly interfered with her ability to assist McCoy in treating him for the puncture wound left behind by the Denevan neural parasite, prompting the doctor to order her either to put aside her feelings or call another nurse to help him. (TOS: "Operation -- Annihilate!")

Three years after confessing her love to Spock, Chapel finally shared a kiss with him. Unfortunately, the situation was forced by the Platonians, against their will. Having sensed their close bond, they adorned her in make-up that gave her the appearance of a Vulcan. Chapel admitted that, despite her long-standing desire to be close to Spock, all she wanted to do, given the humiliation of the situation, was "crawl away and die." (TOS: "Plato's Stepchildren")

Later that year, Harry Mudd provided Lieutenant Chapel with love potion crystals that she used on Spock, much to her embarrassment when they didn't take effect immediately. Though the crystals eventually worked, it wasn't long before Spock realized he was reacting to it and not experiencing genuine feelings of love. Later, when he offered to help her record Mudd's confession, she rebuffed him. (TAS: "Mudd's Passion")

Upon hearing that she'd become a doctor during his brief hiatus from Starfleet, McCoy was reluctant to work with her, as he was of the opinion that she, like other doctors, would argue about every diagnosis he made, rather than take the orders he gave. (Star Trek: The Motion Picture)

Given McCoy's feelings about being "drafted", it's possible he was venting, not criticizing her personally.

The character of Christine Chapel was created by Gene Roddenberry, intending the part to be played by Majel Barrett, with whom the married Roddenberry was having an affair. The creation of the recurring role was Roddenberry's solution to pressure that Barrett frequently put on him, as she was insistent that she play a regular character on Star Trek, even though executives at the television network NBC had fired her as Number One in the unaired original pilot "The Cage". As an executive producer on the original series of Star Trek, Roddenberry planned to ensure that the resultant character of Chapel would definitely recur. (Inside Star Trek: The Real Story, paperback ed., p. 224)

In his reference bookThe World of Star Trek (3rd ed., p. 28), writer David Gerrold reckoned that Chapel "was obviously created specifically" to love Spock and went on to say, "The need to dramatize Spock's Vulcan aloofness requires that a woman fall in love with him and be continually rebuffed. Hence, Nurse Chapel."

In scripts of "The Naked Time", this character was known as Christine Baker and, later, Christine Ducheaux. She was even referred to with the latter name in the final draft shooting script (dated 28 June1966), which went on to describe her as "dark-haired... more starkly attractive than beautiful... a woman capable of startling vitality... superb efficiency...." [1] In a revised draft of the script, this passage of text was minutely changed, with the only alteration being that the words "a woman capable of startling vitality" were moved to the start of the description. Gene Roddenberry renamed the character to Christine Chapel as a pun on "Sistine Chapel". (These Are the Voyages: TOS Season One, Inside Star Trek: The Real Story) In actual dialogue in "The Naked Time", however, she is never referred to as anything other than "Nurse" or "Christine".

Majel Barrett saw her opportunity to appear further in Star Trek by auditioning for the role of Chapel. "I wanted to be a part of it so badly, and I kept watching the scripts that came in, and when this episode ['The Naked Time'] came in, my mind started to go in different directions," Barrett recollected. "So I bleached my hair and waited for Gene [Roddenberry] to come in and take notice of it." (Star Trek Monthly issue 27, p. 44) Barrett, whose hair was now bleached blond, awaited Roddenberry in his office. "I sat there talking to his secretary, Penny, and Gene walked in. He looked at me and at Penny, said, 'Good morning,' and walked in the door... I kept on talking to Penny, and pretty soon Gene came out again, put some papers on Penny's desk, sort of smiled at me, turned around, and walked back in his office. Then the double take happened. He opened the door and said, 'Majel?!' And I said, 'By God, if I could fool you, I can fool NBC.'" (Star Trek - Where No One Has Gone Before, p. 21) Roddenberry agreed. Concluded Barrett, "He said, 'Yes, you can' [....] You just don't come back again when they fire you once, but I so much wanted to be a part of this show." (Star Trek Monthly issue 27, p. 44) Barrett thereafter played Christine Chapel.

An issue that frustrated the show's producers, notably Robert Justman, as well as Majel Barrett herself, was that the character of Chapel was not fleshed out. (Star Trek Magazine issue 144, p. !4) For instance, little canonical information existed about Chapel's life outside of her career in Starfleet. Just after seeing the first footage of Barrett in the role, Justman realized that he didn't much like the performance. He addressed this problem with Gene Roddenberry in the latter's office, saying that Barrett "seemed awkward" in the part. "Gene just smiled," Justman remembered, "as he always did when I told him something he didn't particularly want to hear [....] 'I thought she was fine,' he responded. 'Maybe a little nervous this time, but she'll work out great. It's a new character for her, and she'll get even better as she goes along. I like her a lot in this role.' Pushing him further wouldn't work. But I continued to needle him about it from time to time. His response was always the same: a smile, a short remonstration that she was 'fine' in the role, and then a change of subject. I stopped needling him about it after finally becoming aware of their relationship. Years later, I realized it wasn't the actress I disliked, it was the role. Nurse Chapel was a wimpy, badly written, and ill-conceived character." He particularly found fault with Chapel repeatedly pining for another character – whether it be Spock, as is the case in "The Naked Time", or Roger Korby in "What Are Little Girls Made Of?" (Inside Star Trek: The Real Story, pp. 224-225) Expressing similar sentiments, Barrett confessed, "I didn't care that much for Nurse Chapel, to tell you the truth. She really wasn't that exciting a person or that exciting a character for an actress to play." (Star Trek Monthly issue 38, p. 39) Clarified Barrett, "I was happy with what I did, except there wasn't that much to do. It wasn't that satisfying, but in those days, I couldn't talk Gene into doing any more; again, I was a woman, and they had already fired me once, so I wasn't given too much to do." (Star Trek Monthly issue 27, p. 44)

The script of "What Are Little Girls Made Of?" included the following description of Chapel; "She's a strong, calm woman, very much in control of herself which emphasizes only more for us the flickers of emotions that do occasionally show through." Also, as scripted for that episode, Chapel's abandonment of a career in bioresearch was stated to have been specifically for a position aboard the Enterprise, though this ultimately changed to being an assignment aboard a generic vessel. [2] Regarding Majel Barrett's appearance as Chapel in "What Are Little Girls Made Of?", Robert Justman critiqued, "The close-up shots of her eyes misting over and lower lip quivering were beautifully photographed by cameraman Jerry Finnerman, who used special lighting and diffusion lenses. But this only served to emphasize the lack of character written into the character." (Inside Star Trek: The Real Story, 1997, p. 225)

According to Herb Solow, NBC did notice the same actress whom they had already fired portrayed Chapel. Solow related that – while he was screening a rough edit of "The Naked Time" for a group of NBC execs, well before the series was broadcast – NBC Vice President Herb Schlosser asked him who the performer was, a question Solow agreed to answer later. When they were alone after the screening, Schlosser repeated the inquiry and, upon Solow revealing the name of the actress, the NBC executive realized it was the same controversial performer. Schlosser was therefore initially puzzled about why the Star Trek producers hadn't cast a different actress for the part. "This was one of those times when the truth would be painful for all concerned," stated Solow. "I answered quickly, 'Putting together a cast is like forming an orchestra. Individual actors are unimportant; it's an ensemble thing.'" Schlosser then correctly assumed that Barrett's casting as Chapel was due to her having an affair with someone who had a lot of influence in the Star Trek production team, a suspicion that Solow didn't confirm until after the series had been airing for a while. Also according to him, the news within NBC that the portrayal of Chapel involved Barrett returning to Star Trek led Jerry Stanley – another executive at the television network – to yodel, "Well, well – look who's back." (Inside Star Trek: The Real Story, 1997, pp. 224 & 233) Barrett herself claimed, "For three years, NBC never knew it was the same person." (Star Trek Monthly issue 27, p. 44)

Regardless of whether or nor Barrett actually believed her own claim, it were not only Schlosser and Stanley who found out early, but Desilu Studios Head Lucille Ball as well, and, according to Solow, when she did, she was not amused, not in the slightest; Lucille Ball had by then become well known for her character trait of valuing moral propriety after her failed marriage with Desi Arnaz (which had fallen apart partly due to Arnaz' philandering), and this she expected of her staff and employees as well. When she found out that the married Roddenberry had an illicit affair with Barrett (ironically hired, under her own name Majel Leigh Hudec, by Ball herself for Desilu as a contracted actress, and having personally instructed her in one of her own comedy seminars in 1957. [3][4](X)), she could not abide with this kind of behavior anywhere near her property, and was dead-set on firing the pair of them on the spot. Incidentally, Ball had already wanted to do something similar, albeit at the opposite end of the spectrum, with Mission: Impossible co-stars Barbara Bain and Martin Landau, when she found out that the two were actually a married couple, and wanted to fire them as she suspected a severe case of nepotism, which she could not abide with either. And indeed, this had been the additional reason for Ball for wanting to fire the future Roddenberry couple as well, as she concurrently became aware that he had surreptitiously sneaked an as a blonde disguised Barrett, her new alias (which Ball took as evidence of deliberate deception, not entirely unjustified), back into the Star Trek production as Christine Chapel against the express wishes of NBC. Through an intermediary, her personal publicist Howard McClay, Solow had in both cases – as Mission was also produced under his auspices – the toughest of times to convince the headstrong Ball otherwise. (Inside Star Trek: The Real Story, 1997, p. 223; These Are the Voyages: TOS Season One, 1st ed, pp. 25-27)

Christine Chapel turned out to be highly unpopular among some fans of Star Trek's original series. "It was because of her love for Spock and his occasional moments of gentleness toward her that Christine Chapel was largely disliked among the Trekkies who adored Spock," explained David Gerrold. "Female fans saw her as a threat to their own fantasies and male fans saw her as a threat to Spock's Vulcan stoicism." However, the fans who met Majel Barrett were often surprised by how beautiful she was. Gerrold concluded, "They just couldn't see it in her as Chapel because of the relationship between her and Spock." (The World of Star Trek, 3rd ed., p. 28)

Christine Chapel was intended to be included in the ultimately aborted television series Star Trek: Phase II, in which her promotion to doctor was planned to be established. The Writers'/Directors' Guide for that series said of the character, "Introduced in Star Trek I as Nurse Chapel, her medical degrees have been accepted by Starfleet, and she has returned to the U.S.S. Enterprise to serve as McCoy's associate. She is second in command of the ship's medical section, and McCoy seems to enjoy passing on to her every duty he finds too boring, irritating or annoying to himself. Yet outside of Captain Kirk, she is probably McCoy's closest confidante. An expert in psychotherapy, she has unusual ability to teach patients how to use the healing powers of their own bodies." (The Making of Star Trek: The Motion Picture, p. 119)

In character notes that Gene Roddenberry wrote for Star Trek: The Motion Picture, Chapel was mentioned in the note about Dr. McCoy and was described as being influenced by the fact that McCoy was dealing with a great deal of pressure at the time of the film, even to the point of almost causing him to suffer a nervous breakdown. The section regarding Chapel stated, "[She] must take on an overly large portion of the load of treating the sick, and is likewise subject to breakage." (The Making of Star Trek: The Motion Picture, p. 102) Majel Barrett was delighted that, in The Motion Picture, Chapel was promoted to doctor status and that she herself was not required to ruin her hair by dying it blond to match her TOS appearances as Chapel. In the film, Barrett's portrayal of Chapel was partly based on the description of the character from the Writers'/Directors' Guide for Phase II. (The Making of Star Trek: The Motion Picture, p. 119) Her appearance in The Motion Picture was in keeping with the fact that long hairstyles were disallowed in that film. (The Making of Star Trek, p. 142) However, Majel Barrett had qualms about her appearance as Chapel in The Motion Picture, confessing, "I really didn't consider my work in the first one to be that great an experience." (Starlog #116)

When asked why she herself was absent in Star Trek II: The Wrath of Khan and Star Trek III: The Search for Spock, Majel Barrett stated, "The fact that Gene really didn't have that kind of involvement in the second and third movies was probably the reason. There was a new producer on the pictures and I just don't think they, or anybody, wanted Mrs. Roddenberry running around. I'm sure it was politics. Since then, many things have been ironed out and I certainly have greater hopes for Star Trek IV." (Starlog #108, July 1986, p. 56)

In the script for Star Trek IV: The Voyage Home, Chapel was described as a "Starfleet Medical Officer whose history in Star Trek is known to all." The same script featured her in a short, ultimately excised scene. Set in the Federation Council Chamber, the scene detailed Commander Chapel meeting with Sarek upon his arrival there. She thanked him for coming but admitted to being unsure whether he was too late to testify at the then-ongoing trial of Admiral Kirk and the senior crew of the Enterprise. [5] Noted Majel Barrett, "I just had a couple of lines with Sarek, so it was really nothing of consequence." However, Barrett also considered that this scene would have been her "only real scene" in the movie. Chapel's role in Star Trek IV is so minimal that Barrett hypothesized, "If no one had called me Commander Chapel, the audience wouldn't really know that I was there." Longing to have more involvement in Star Trek, she proclaimed, "Somewhere Chapel got lost." On the other hand, Barrett also related about her brief inclusion in Star Trek IV, "I am grateful for having been in it after not being in Star Trek II or III [....] I loved it, I had such a great time." (Starlog #116)